This invention relates to novel couplers for use in hair coloring compositions comprising one or more oxidative hair coloring agents in combination with one or more oxidizing agents. The invention also relates to hair coloring compositions of these novel couplers and to coloring or dyeing of hair using compositions containing these couplers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, and 5-amino-2-methylphenol. A majority of the shades have been produced with dyes based on p-phenylenediamine.
DE 4422603 describes oxidative hair dyes based on 4,5-diamininopyrazoles and m-phenylenediamine derivatives. Especially (3-dimethylamino-phenyl)-urea couples with 4,5-diaminopyrazole to provide a blue color. However, the intensity of the blue is not very strong probably due to the solubility of the compound. Therefore, there is a need for new couplers for use in oxidative hair dyeing compositions and systems to increase dye-uptake, resulting in strong blue coloration.
This invention provides novel couplers of the formula (1): 
wherein X is selected from halogen and R5SO4 where the halogen is preferably Cl, Br or I; R, R1, R2 and R5 are each individually selected from C1 to C22 alkyl and C1 to C22 mono or dihydroxyalkyl and R3 and R4 are each individually selected from C1 to C6 alkyl, C1 to C6 hydroxyalkyl, C1 to C6 alkoxy, C1 to C6 aminoalkyl or R3 and R4 together form a C1 to C5 alkylene group. Preferably X is Cl, Br, I and R5SO4 where R5 is C1 to C4 alkyl, more preferably methyl; and preferably R, R1, R2, R3 and R4 are each individually C1 to C4 alkyl, and more preferably methyl. These novel couplers are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel couplers provide for dyeing of hair that provides color or shades that possess good wash fastness and do not undergo the significant changes on exposure to light or shampooing.
Preferred coupler compounds of this invention are those of formula (1) 
wherein X is selected from Cl, Br I and R5SO4 where R5 is C1 to C3 alkyl; and R, R1, R2, and R5 are each individually a C1 to C3 alkyl group, preferably methyl groups; and R3 and R4 are individually selected from C1 to C3 alkyl groups, preferably methyl groups.
Especially preferred couplers of this invention are the following compounds:
quatererized N-[2-(trimethylamino)ethyl]Nxe2x80x2-[3-(dimethylamino)phenyl]urea iodide, chloride, bromide and methyl sulfate salts;
The novel coupler compounds of formula (1) of this invention are readily prepared according to the following reaction sequence where X, R, R1, R2, R3, R4 and R5 are as defined hereinbefore: 
As a example of such synthesis an aminobenzoic acid of formula (2) is subjected to a Curtius rearrngement with diphenylphosphoryl azide (DPPA) and triethylamine (Et3N) in toluene to give the isocyanate of formula (3). Reaction of this isocyanate with a disubstituted ethylene diamine (H2Nxe2x80x94CH2xe2x80x94CH2xe2x80x94Nxe2x80x94R1,R2) produces the urea compound of formula (4). Reaction of this urea compound with the quaternization reagent R-X produces the quaternized urea compounds of formula (1).